The subject matter described herein relates generally to sensors and, more particularly, to sensors for high-temperature environments and methods for assembling the same.
At least some known high-impedance sensor assemblies include sensing elements manufactured for high-temperature environments up to and exceeding approximately 225 degrees Celsius (° C.) (437 degrees Fahrenheit (° F.)). However, known electronic devices coupled in communication with these known sensing elements may not operate consistently and reliably in environments with temperatures above approximately 225° C. (437° F.). Many industrial applications include environments with temperatures ranging from about −55° C. (−67° F.) to about 600° C. (1112° F.) substantially continuously, i.e., for exposure periods over an extended period of time, e.g., exceeding approximately 5,000 hours. Therefore known high-temperature, high-impedance sensor assemblies require special adaptive equipment to facilitate operating with a desired signal-to-noise ratio (SNR) and survivability in rugged, high-temperature environments, up to, and exceeding, approximately 225° C. (437° F.).
Such special adaptive equipment may include use of auxiliary cooling devices to facilitate operating electronic devices within the sensor assemblies in high temperature environments at and/or above approximately 225° C. (437° F.). Such auxiliary cooling devices may include heat exchange devices, e.g., cooling coils coupled to a fluid coolant system. However, these auxiliary cooling devices increase the costs of assembling the sensor assemblies and add another potential point of failure to such assemblies. Moreover. the size and/or weight of the auxiliary cooling devices are often prohibitive.
Also, such special adaptive equipment may include mineral insulated (MI) cable which facilitates operative connectivity with devices that receive signals transmitted from the sensing elements. However, while such MI cable is more sturdy and robust than standard shielded cable, and is therefore sometimes referred to as “hardline cable”, MI cable is more costly to purchase than standard shielded cable. Also, due to the sturdiness of the cable, MI cable is difficult to bend and is difficult to route through industrial facilities, requiring special tooling, thereby further increasing installation costs. Furthermore, for high-temperature environments of approximately 225° C. (437° F.) or above, the electronic devices are separated from the sensing elements. In such situations, the electronic devices may be positioned a significant distance from the sensing elements, thereby further increasing the costs of installation and possibly adversely affecting operating reliability due to unforeseen cable failures and increased susceptibility to noise therein.